A well known theorem by Elliott Lieb allows to determine the spin of the ground state for a repulsive Hubbard model in bipartite lattices. Building on this result we consider the problem of single atom vacancies in a bipartite lattice and we show that for the repulsive Hubbard model it is possible to build entangled states for spins located on spatially separated vacancies. We show that these states belong to a separate Hilbert space and hence are topologically protected.